Polyphenylene ether resins are well known in the chemical arts and exhibit desirable chemical, physical and electrical properties over a wide temperature range. This combination of desirable properties renders polyphenylene ether resins suitable for a broad range of applications, many of which have not been susceptible to the use of polymers or polymer mixtures or alloys before. Often times polyphenylene ether resins are blended or copolymerized with other resins to produce a polymer alloy system with improved properties over the nonblended resins. These improved characteristics, of course, further increase the utility of polyphenylene ether polymers of resins. PCT published application 87850 describes blends of polyphenylene ether resins with polyesters. It discloses that polyester such as poly(alkylene dicarboxylates) can be added to polyphenylene ether resins in order to improve the resistance of these resin blends to nonpolar solvents such as gas.
A requirement for the commercial use of blend compositions of polyphenylene ether and polyester polymers is that the polyester polymers not undergo substantial thermal degradation during processing when the blends are subject to common processing temperatures for polyphenylene ethers. However, these temperatures exceed the thermal decomposition temperatures for many polyester polymers, therefore limiting the range of process temperatures which can be used for such blends. The thermal degradation of these polyester polymers results in a very narrow processing temperature window for injection molding resin blends of polyphenylene ethers/polyesters.
The blend compositions of the present invention possess a lower processing temperature range than state of the art materials while maintaining the advantageous characteristics otherwise associated with such blends. Thus the blends of the present invention have a broader range of practical applications than state of the art blends.